Re: [PATCH 0/2] Improved node descriptions

[Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>]

On Tue, Feb 22, 2011 at 04:03:29PM -0800, Roland Dreier wrote:
> On Tue, Feb 22, 2011 at 3:43 PM, Jason Gunthorpe
> <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org> wrote:
> > Doing it in userspace makes generating the node description changed
> > trap simpler?
> 
> Hmm... how many places can do sethostname()?  Seems easier to
> catch in the kernel than hook every place in userspace.  (Although
> there's no kernel hook right now)  I do agree it would be good to
> have some idea of how we could generate the "node desc changed"
> trap at appropriate times.

Wasn't thinking about 100% perfection, just if DHCP is the concern it
shouldn't be hard to hook that one place.

> > I just wonder if this is a big pain to do right, what about charsets, IDN,
> > and ugly details like that?
> 
> Does anyone expect to care about non-ASCII node descs?
> What can we sensibly do except take what we're given?

node desc is UTF-8, hostname is IDNA, a conversion is required, see RFC
3490.

Does anyone care? Who knows, but very pedantically it is wrong to just copy
the host name byte by byte. I only mention it to point out that it is 
trivial to do what Mike did, somewhat harder to do % escaping like you
suggest and solve the multiple HCA problem, harder still to trap
sethostname() and generate a trap, and extra special hard to correctly
handle character sets on top of all that. :)

So, is it still trivial to do it in the kernel?

Jason
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